Resistor structure



' Jan. 5, 1954 R. E. DU BOIS RESISTOR STRUCTURE Filed Feb. 27, 1952 INVENTOR ROBERT E. Du BOIS &

ATTORNEY Patented Jan. 5, 1954 UNITED STATES i r ilENT OFFICE 6 Claims.

This invention relates generally to electrical resistance structures and more specifically to the mounting structure for a plurality of sheet metal resistors secured together in face to face spaced relationship.

The primary object of the invention is to provide a mount for a plurality of spaced resistor grids which is temperature compensating in na ture for preventing the warping or deformation of the grids when they become heated.

A more specific object of the invention is to provide a mounting frame for a plurality of resistors secured together in spaced relationship in which resilient temperature compensation elements are utilized to secure the resistors to the mounting frame.

Another object of the invention is to provide a mounting frame for a plurality of resistors secured together in spaced relationship in which a plurality of spring elements are utilized to secure the resistors in the mounting frame, thereby acting as shock absorbing and temperature compensation elements.

A further object of the invention is to provide a mounting frame for a plurality of resistors secured together in spaced relationship by bolts, in which spiral springs are utilized between the securing bolts and the frame to connect the two together while compensating for resistor expansion within the frame under heat and while coinpensating for vibration shocks.

Another object of the invention is to provide a mounting frame for a bank of resistor elements which are secured together in spaced non-movable relationship in which resilient elements are utilized to connect the frame to the resistor bani;-

for temperature and vibration shock compensation.

A further object of the invention is to provide a mounting frame for a bank of spaced. resistors in which resilient elements are utilized to con" nect the bank of resistors to the frame in such a manner as to allow for a substantial expansion of the resistor bank longitudinally under heat and to restrict any tendency toward lateral displacement of the bank within the frame.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims, certain embodiments and details of construction of which are shown in the accompanying drawings in which:

.igure 1 is a partial end elevational view of a typical resistor bank to which this invention is applied;

Figure 2 is a partially sectioned view taken along the line 2-2 of Fig. 1; and

Figure 3 is a sectioned view in side elevation taken along the line 3-3 of Fig. 2.

Resistor grids expand and contract in service due to heating, and unless the connection to the mounting frame allows for this expansion, an unnecessary strain is set up in the grids causing warping, breakage, and possible short-circuiting. The prior art has allowed for this expansion by providing elongated holes in the and frame and permitting the grid supporting bolts to move along the elongated holes when the resistor grids were heated. This method of mounting a resistor bank necessitated the use of loose fitting washers or collars over the elongated holes so as not to restrict the movement of the support bolts, and resulted in a resistor bank with loose and rattling end frames. This looseness permitted a general deterioration and breakage of the entire resistor bank and its ceramic insulating tubes and washers under heavy vibrational strains.

The present invention provides a novel and economical means for overcoming the above difiiculties encountered in the prior art.

Referring particularly to Figure l, a plurality of spaced resistor grids I are mounted in a car rying frame shown generally at 2. Ihe grids I are generally of sheet metal and may be of any desired configuration. The frame 2, which is,

shown consisting of end members 3 and 4, and a head member 5 secured to the end members 3' and 3 by bolts 6 and '7 respectively, may be of any desired construction, the exact detail of which is not pertinent to the present invention. The grids l are secured together in spaced relationship on support bolts 8 and 9. Insulating the rids from the bolts 2 and 9 are ceramic sleevesiii and M respectively. Ceramic washers 12 are provided over sleeves iii and II to space the grids laterally of each other. Connecting leads or washers (not shown) may be provided for connecting the together in any desired relationship, such connection not being pertinent to.

the invention.

Referring to Figures 2 and 3, the bolt 8 is seen to project through hole (3 in end member t. Welded or otherwise secured to the bolt 8 at point i i is one end of a helical spring l5. The other end of spring i5 is welded or otherwise secured to the end member 4 at l6. The spring I5 is desirably rather stiff in nature and is made of a highly resilient steel alloy. A similar spring l5 also connects the other end of bolt 8 to the end member 3, although this detail is not shown.

The bolt 3 is shown in Fig. 1 to be tapped at either end to receive threaded and member securing bolts 11. This construction, however, is

not pertinent to the invention and. mounting springs l may be provided for bolt 9 in a manner similar to that for bolt 8. When the springs are used at all points of connection between the bolts and the frame members 3 and 4, the transmission of vibrational shocks to grids l, as applied to the frame 2, is reduced to a minimum.

It is obvious that other spring designs, or rubber, could Lbe substituted for the spring 7 l5 as shown. Rubber, however,1is-subiect to rapid deterioration under high heat conditions. Other spring designs, such as coil springs obviously could be used but are not preferred, astheghelical spring lends itself to ready connection and will permit planar movement while -.-resistin;g trans-planar movement.

The operation of the invention is-q'uite obvio'us. When electrical currents are applied to theegrids I, they will heat up and expand in accordance with their inherent .coeiiicient of, expansion. 'The springs l5 will allow 'suenexpansien' byjper'mittingthe bolt i8 tofmove upwardlyeas viewed in the figures. The'springs l5 .wilLlat fthe same time, resist any. tendency ofthegrids tojmove transversely of the planes of saids'prings, thereby maintaining the longitudinal alignment of. grids l. Normally then, under room temperature condition, the bolt-8 will beheld. by the spring in in end members 3,-and'4. .Whenthegrids are heated, the bolt-8- will move upwardly out of its central position to compensate. fora expansion of grids: I, and when the grids I are subjected to no electrical currents, and colder than temperature conditions exist-the bolt .8 willmove downwardly from thecentralepositionwithin the "bank to: a mounting framexwhile, simultaneously allowing, in saidconnection, ionexpansionand contraction of' the gridsof the'resistorr-banlr and -ior any: tendency: toward: misalignment of ,the

g'rids :of .theresistor-bank.

What L'cla imis:

1; An electrical resistance structure comprising a frame -witha pair of end members; said' end members beingrboredi at one or morewpo'ints: to

- provide holesftherethroughya pair of resistor grid supporting bolts carried: by said frame; at

least one of said-bolts "extending through "the holesin the endmembers of the ira-me and being of substantially less'di'ameter than'jthe end member' hole, and helical: spring-connected to ach -end of the-bolt and to the end'member -in'the plane of "the end member to w permit-expansion J and contractionof theresistor gr-id by: allowing said supporting bolt-to move.

-2. An electrical-resistance structure comprisinga frame-with a pair of-end members saidend members being bored at one orinore -po'ints to substantially central position :within the holes. 13

provide holes therethrough, a pair of resistor grid supporting bolts carried by said frame, at least one of said bolts extending through the holes of the end members of the frame and being of substantially less diameter than the end member hole, and resilient means within the holes of the end members and connecting between said end members and said bolt to permit relative movement of the bolt withrespect to the frame.

13 An electrical resistance structure comprising a frame with apair of end members, said end members being bored at one or more points to provide holes therethrough, resistor rid supportingmeans, and resilient means within the holes of-the end members and connecting between said end members and said supporting means to permitrelative movement of the bolt with respect vto the frame.

l. An el ctrical resistance structure comprising a frame with a pair of end members, said end members being bored at one or more opposed points to provide holes therethrougha resistor grid supporting means extending transversely-of theend members and through the opposed holes in the end members, and resilient means within the holes of the end members and connecting between said end members and said supporting 17182115 to permit the supporting means to move axially of the said end members.

5. rlneleotrical resistance structure comprising a frame with a pair of endmembers, said end members bored at two points'to provide matching holes therethrough, plural'resistor or grid supporting means extending. transversely of the end members and through the opposed matching holesinthe end members, and resilient means within the holes-of the end members and con necting between saidend meznbersand said supporting means to permit the supporting means to move axially of the said end-members.

. 6. rinelectrical resistance structure comprising a frame with a pair of endimembers, saidend members being bored at one or more opposed points to provide holes therethrou'gna resistor grid supporting means extending .transversely of the end members and through the opposed holes in theendmeznbers, and helical spring means within the holes of the end members and connecting between said endmembers and said supporting means to permit the supporting. means t more axially of said end members.

-RO 3ER-T E. DU BOIS.

Bei'erences Git-ed in- .the file Of, this patent UNITED STATES PATENTS "Number Name Date 1,065,015 Youmans V June 17; 1913 FOREIGN PATENTS Number Country Date 3,191 Great-Britain of 1909 

